code: def testRunningStat(self):
      for shp in ((), (3,), (3, 4)):
          li = []
          rs = RunningStat(shp)
          for _ in range(5):
              val = np.random.randn(*shp)
              rs.push(val)
              li.append(val)
              m = np.mean(li, axis=0)
              self.assertTrue(np.allclose(rs.mean, m))
              v = (
                  np.square(m)
                  if (len(li) == 1)
                  else np.var(li, ddof=1, axis=0)
              )
              self.assertTrue(np.allclose(rs.var, v))
  
file_path: ray/rllib/tests/test_filters.py
imports: import numpy
  import unittest
  import ray
  from ray.rllib.utils.filter import RunningStat, MeanStdFilter
  from ray.rllib.utils import FilterManager
  from ray.rllib.tests.mock_worker import _MockWorkerSet
label_desc: Use image node_id 1 for calling the RunningStatTest obj's underlying member method code with example usage: obj.testRunningStat() without return types